Safety apparatus for arresting a fall of a worker

ABSTRACT

A safety apparatus ( 10 ) includes a frame unit ( 12 ) placed on a surface ( 102 ). A cable ( 62 ) is mounted around a pulley ( 60 ) rotatably mounted to the frame unit ( 12 ) about a rotation axis ( 58 ). A slide ( 90 ) is slideably mounted to the frame unit ( 12 ) along a slide axis ( 92 ) at a non-parallel angle to the rotation axis ( 58 ) and movable between upper and lower positions. The cable ( 62 ) is attached between the slide ( 90 ) and a worker ( 100 ) on the surface ( 102 ). A biasing member ( 110 ) is mounted between the slide ( 90 ) and the frame unit ( 12 ) and biases the slide ( 90 ) from the lower position to the upper position. An engaging member ( 120 ) is mounted to the slide ( 90 ) to move therewith. The engaging member ( 120 ) is above the surface ( 102 ) when the slide ( 90 ) is in the upper position. If the worker ( 100 ) falls from the surface, the engaging member ( 120 ) is moved downward and grips the surface ( 102 ) under the action of force resulting from falling of the worker ( 100 ) to retain the safety apparatus ( 10 ) on the surface and, thus, arrests the fall of the worker ( 100 ) from the surface ( 102 ).

BACKGROUND OF THE INVENTION

The present invention relates to a safety apparatus for arresting a fallof a worker and, more particularly, to a safety apparatus for arrestinga fall of a worker from a surface.

A safety apparatus should generally be provided to protect and allowfree movement of a worker on a surface such as a flat roof surface, anupper story of a multi-story building being constructed, or the groundadjacent a precipice. The safety apparatus includes an engaging memberfor gripping the surface. A harness is attached between the worker andthe safety apparatus. The engaging member of the safety apparatus gripsthe surface if the worker falls from the surface under the action of theforce resulting from falling of the worker and transmitted to theengaging member via the harness. In an approach, the engaging memberpivots about a pivot axis and grips the surface under the action of theforce. However, the penetration depth of the engaging member can be anissue, leading to insufficient gripping force and risking movement ofthe safety apparatus. Furthermore, the safety apparatus and otherequipment can be hoisted by a crane or the like to the surface such as aroof. Conventional safety apparatuses include a plurality of invertedU-shaped attachment elements to which hooks of the crane are engaged.However, the hooks are liable to unhook through the bottom opening ofthe inverted U-shaped attachment elements if the hook lines becomeslack.

Thus, needs exist for a safety apparatus that can reliably arrestfalling of workers from a surface and/or that can avoid unhooking whilehoisting the apparatus to the surface.

BRIEF SUMMARY OF THE INVENTION

The present invention solves these needs and other problems in the fieldof safety of workers working on an elevated surface by providing, in apreferred aspect, a safety apparatus including a frame unit adapted tobe placed on the surface. A pulley is rotatably mounted to the frameunit about a rotation axis spaced from the surface. A cable is mountedaround the pulley and includes first and second ends. The second end ofthe cable is adapted to be connected to the worker. The pulley islocated intermediate the first and second ends of the cable. A slide isslideably mounted to the frame unit along a slide axis at a non-parallelangle to the rotation axis and movable between upper and lowerpositions. The first end of the cable is attached to the slide. Forceresulting from a fall of a worker from the surface is transmitted to theslide via the cable. A biasing member is mounted between the slide andthe frame unit and biases the slide from the lower position to the upperposition. An engaging member is mounted to the slide to move therewith.The engaging member is above the surface when the slide is in the upperposition. The engaging member grips the surface when the slide is in thelower position, preventing further falling of the worker.

In the most preferred form, an attachment member is connected to thesecond end of the cable, and a harness is connected between theattachment member and the worker. The biasing member includes a cylinderhaving a lower end fixed to the frame unit and an upper end fixed to theslide. The engaging member includes first and second spaced teeth eachextending from the slide. Each of the first and second teeth is planarand at an acute angle relative to a base extending along the slide axis.

In a further preferred aspect, the present invention provides a liftingattachment for a frame unit adapted to be lifted on a surface. Thelifting attachment includes an attach element having first and secondsides spaced in a first direction. The attachment element furtherincludes first and second edges extending between the first and secondsides and spaced in a second direction perpendicular to the firstdirection. The attachment element further includes third and fourthedges extending between the first and second sides and between the firstand second edges and spaced in a third direction perpendicular to thefirst and second directions. A first passage extends between the firstand second sides in the first direction and extends from the first edgetowards but spaced from the second edge in the second direction. Thefirst passage is parallel to but spaced from the third and fourth edgesin the third direction. A second passage extends perpendicularly betweenthe first and second sides in the first direction and extends from thefirst passage towards but spaced from the third edge in the seconddirection. The second passage is parallel to but spaced from the firstand second edges and spaced from the fourth edge. In the most preferredform, the attachment element is formed homogeneously from the samematerial and extends integrally between the first and second sides inthe first direction, extends integrally between the first and secondedges in the second direction and extends integrally between the thirdedge and the second passage in the third direction.

The present invention will become clearer in light of the followingdetailed description of illustrative embodiments of this inventiondescribed in connection with the drawings.

DESCRIPTION OF THE DRAWINGS

The illustrative embodiments may best be described by reference to theaccompanying drawings where:

FIG. 1 shows a diagrammatic perspective view of a safety apparatusaccording to the preferred teachings of the present invention with aharness of the safety apparatus attached to a worker on a surface.

FIG. 2 shows a rear elevational view of safety apparatus of FIG. 1.

FIG. 3 shows an elevational view of a portion of the safety apparatus ofFIG. 1.

FIG. 4 shows an elevational view of a slide and an engaging member ofthe safety apparatus of FIG. 1.

FIG. 5 shows a cross sectional view of the slide and engaging member ofFIG. 4 according to section line 5-5 of FIG. 4.

FIG. 6 shows a top view of the slide and engaging member of FIG. 4.

FIG. 7 shows a rear elevational view of the safety apparatus of FIG. 1with the slide moved to a lower position.

FIG. 8 shows an enlarged view of a portion of the safety apparatus ofFIG. 1, illustrating detailed structure of an attachment element.

FIG. 9 shows a view similar to FIG. 8, with a hook engaged with theattachment element.

All figures are drawn for ease of explanation of the basic teachings ofthe present invention only; the extensions of the figures with respectto number, position, relationship, and dimensions of the parts to formthe preferred embodiments will be explained or will be within the skillof the art after the following teachings of the present invention havebeen read and understood. Further, the exact dimensions and dimensionalproportions to conform to specific force, weight, strength, and similarrequirements will likewise be within the skill of the art after thefollowing teachings of the present invention have been read andunderstood.

Where used in the various figures of the drawings, the same numeralsdesignate the same or similar parts. Furthermore, when the terms“first”, “second”, “third”, “fourth”, “lower”, “upper”, “top”, “bottom”,“inner”, “outer”, “side”, “end”, “edge”, “portion”, “section”,“horizontal”, “vertical”, “spacing”, “length”, “width”, and similarterms are used herein, it should be understood that these terms havereference only to the structure shown in the drawings as it would appearto a person viewing the drawings and are utilized only to facilitatedescribing the invention.

DETAILED DESCRIPTION OF THE INVENTION

A safety apparatus for arresting a fall of a worker according to thepreferred teachings of the present invention is shown in the drawingsand generally designated 10. According to the preferred form shown,safety apparatus 10 is placed on an elevated surface 102. Surface 102can be a flat roof surface, an upper story of a multi-story buildingbeing constructed, or the ground adjacent a well, a shaft, or the like.Safety apparatus 10 protects and allows free movement of a worker 100 onsurface 102.

According to the preferred form shown, safety apparatus 10 includes aframe unit 12 adapted to be placed on surface 102. Frame unit 12includes a frame 14 having a deck 16 movably supported above surface 102by four wheels 20. Deck 16 includes upper and lower faces spaced in avertical direction perpendicular to surface 102. A slot 18 extends fromthe upper face through the lower face of deck 16. A hitch 22 can beattached to a rear end of frame 14 such that frame unit 12 can be towedmanually or by a tractor or the like on surface 102. If desired, wheels20 can be replaced with skids or other forms of movement providingelements. Likewise, safety apparatus 10 can include a parking device toavoid movement of wheels 20 including but not limited to brakes forwheels 20. Hitch 22 can be of any desired form as conventional includingbut not limited to of a commercially available type. A utility box 24can be mounted on top of frame 14 and can receive accessories requiredfor protecting worker 100 as well as tools for repair or other purposes.Frame unit 12 further includes a plurality of rollers 26 rotatablymounted to frame 14 by brackets 27. It can be appreciated that rollers26 can be of any desired form as conventional including but not limitedto of a commercially available type and can be mounted to frame 14 byany suitable provision.

According to the preferred form shown, safety apparatus 10 furtherincludes a plurality of lifting attachments 28 mounted to frame 14 toallow frame unit 12 to be lifted on surface 102 by a crane or the like.Although four lifting attachments 28 are shown at four corners of frame14 in the preferred form, the number, location, and positioning oflifting attachments 28 can be varied according to the teachings of thepresent invention.

According to the preferred teachings of the present invention, eachlifting attachment 28 includes an attach element 30 having first andsecond sides 32 and 34 spaced in a first direction. Attachment element30 further includes first and second edges 36 and 38 extending betweenfirst and second sides 32 and 34 and spaced in a second directionperpendicular to the first direction. Attachment element 30 furtherincludes third and fourth edges 40 and 42 extending between first andsecond sides 32 and 34 and between first and second edges 36 and 38 andspaced in a third direction perpendicular to first and seconddirections. A first passage 44 extends between first and second sides 32and 34 in the first direction and extends from first edge 36 towards butspaced from second edge 38 in the second direction. First passage 44 isgenerally parallel but spaced from third and fourth edges 40 and 42 inthe third direction. A second passage 46 extends between first andsecond sides 32 and 34 in the first direction and extends generallyperpendicularly from first passage 44 towards but spaced from third edge40 in the second direction. Second passage 46 is generally parallel tobut spaced from first and second edges 36 and 38 and spaced from fourthedge 42. In the most preferred form shown, an extension 48 extendsbetween first and second sides 32 and 34, extends from first passage 44through fourth edge 42 in the third direction and extends from firstedge 36 towards but spaced from second edge 38 in the second direction.Second passage 46 is intermediate extension 48 and second edge 38 in thesecond direction. Attachment element 30 is formed homogeneously from thesame material and extends integrally between first and second sides 32and 34 in the first direction, extends integrally between first andsecond edges 36 and 38 in the second direction and extends integrallybetween third edge 40 and second passage 46 in the third direction.Attachment element 30 thus formed includes a substantially L-shaped leg50 having a vertical section 52 and a horizontal section 54 extendingperpendicularly to vertical section 52. In the most preferred formshown, after attachment element 30 is mounted to frame 14, the firstdirection is a width direction of frame 14, the second direction is alength direction of frame 14, and the third direction is the verticaldirection.

Frame unit 12 can be hoisted by a crane onto surface 102 through use ofa plurality of hooks 108 each engaged in second passage 46 of one ofattachment elements 30 and a plurality of cables 106 each connectedbetween one of hooks 108 and a boom of the crane. Each hook 108 can bemoved through first passage 44 of one of attachment elements 30 in thelength direction of frame 14 until it is stopped by vertical section 52of one of legs 50. Each hook 108 can then be moved upward in thevertical direction into second passage 46 of one of attachment elements30. Horizontal section 54 of leg 50 guides hook 108 and prevents hook108 from disengaging from first passage 44 while hook 108 is passingthrough first passage 44. Due to the shape of attachment elements 30according to the teachings of the present invention, hooks 108 can bereliably guided into and retained in second passages 46 of attachments30 without the risk of unintentional unhooking that often occurs inconventional inverted U-shaped attachment elements if one or more cable106 becomes slack.

According to the preferred form shown, safety apparatus 10 furtherincludes a pulley 60 rotatably mounted to frame unit 12 about a rotationaxis 58 spaced from surface 102 and parallel to the length direction offrame 14 in the most preferred form shown. A cable 62 is mounted aroundpulley 60 and includes first and second ends 64 and 66. Pulley 60 islocated intermediate first and second ends 64 and 66 of cable 62. Anattachment member 68 is connected to second end 66 of cable 62 and hascross sections perpendicular to cable 62. In the most preferred formshown, attachment member 68 includes a plate 70 having first and secondsides 72 and 74 extending at non-parallel angles to cable 62. In thepreferred form shown, first and second sides 72 and 74 are parallel andextend generally perpendicular to cable 62. A plurality of loops 76 isformed on first side 72, and a ring 78 is formed on second side 74.Second end 66 of cable 62 is attached to ring 78. Cable 62 passesthrough a passage 86 defined between attachment member 68 and pulley 60.Passage 86 has cross sections perpendicular to cable 62 and smaller thanthe cross sections of attachment member 68. A harness 80 has a first end82 adapted to be connected to worker 100 and a second end 84 attached toone of loops 76. The number of loops 76 can be varied according to theteachings of the present invention depending upon the total amount offorce that safety apparatus 10 can handle without moving off surface102. The number of workers 100 should not exceed the number of loops 76.

According to the preferred form shown, safety apparatus 10 furtherincludes a slide 90 slideably mounted to frame unit 12 along a slideaxis 92 and movable between upper and lower positions. Slide axis 92 isat a non-parallel angle to and spaced from rotation axis 58.Furthermore, slide axis 92 is at a non-parallel angle A in a range of60°-85° relative to surface 102. In the most preferred forms shown,angle A between slide axis 92 and surface 102 is in the order of 74°.Slide 90 slideably extends through slot 18 of frame 14 and includesupper and lower ends 94 and 96 spaced along slide axis 92. First end 64of cable 62 is attached to upper end 94 of slide 90. Pulley 60 islocated intermediate slide 90 and plate 70 in the width direction offrame 14. Furthermore, slide 90 includes U-shaped cross sectionsperpendicular to slide axis 92 and includes first and second arms 88 anda connecting wall 98 extending between first and second arms 88. Each offirst and second arms 88 includes a bend 89 extending perpendicularlyfrom a distal edge thereof. Pulley 60 extends intermediate first andsecond arms 88 in the length direction of frame unit 12.

According to the preferred form shown, safety apparatus 10 furtherincludes a biasing member 110 mounted between slide 90 and frame unit 12to bias slide 90 from the lower position to the upper position. In themost preferred form shown, biasing member 110 is in the form of acylinder extending through slot 18 and having an upper end 112 fixed toa tab 56 located at upper end 94 of slide 90 and a lower end 114 fixedto frame unit 12 at a location intermediate pulley 60 and attachmentmember 68 in the width direction of frame 14. The cylinder can be of thepneumatic or hydraulic type. Furthermore, biasing member 110 can be ofother forms and types according to the teachings of the presentinvention. As an example, basing member 110 can include a cushioningspring and a cushioning rod extending through the cushioning spring andattached between slide 90 and frame 14.

Rollers 26 support sliding movement of slide 90 between the upper andlower positions along slide axis 92 in a manner to reduce frictionalinteraction. In the most preferred form shown, some of rollers 26 are incontact with outer faces of bends 89 of slide 90, and the remainingrollers 26 are in contact with an outer face of connecting wall 98 ofslide 90. Other provisions for slideably supporting slide 90 relative toframe unit 12 would be within the skill of the art.

According to the preferred form shown, safety apparatus 10 furtherincludes an engaging member 120 mounted to slide 90 to move therewith.Engaging member 120 includes a base 122 mounted to lower end 96 of slide90. Base 122 extends along slide axis 92 and includes a serrated bottom124. Engaging member 120 further includes first and second spaced teeth126 and 128 each extending from base 122. Each of first and second teeth126 and 128 includes a first side 132 and a second side 134 secured tobase 122 at a location above serrated bottom 124. Second side 134 ofeach first and second teeth 126 and 128 is intermediate first side 132and slide 90 and is parallel to first side 132 in the most preferredform shown. Each of first and second teeth 126 and 128 further includesinner and outer surfaces 136 and 138 extending between first and secondsides 132 and 134. A first spacing between first sides 132 of first andsecond teeth 126 and 128 is less than a second spacing between secondsides 134 of first and second teeth 126 and 128. The first spacing canbe 35%-50% of the second spacing. In the most preferred form shown, thefirst spacing is in the order of 43% of the second spacing.

According to the preferred form shown, each of first and second teeth126 and 128 further includes top and bottom edges 140 and 142 extendingbetween inner and outer surfaces 136 and 138 and between first andsecond sides 132 and 134. In the most preferred form shown, top edge 140is perpendicular to first and second sides 132 and 134. Furthermore,bottom edge 142 of each of first and second teeth 126 and 128 iswedge-shaped and includes a tip 144 and has decreasing widths withincreasing spacing from top edge 140. Serrated bottom 124 of base 122 islocated intermediate second side 134 and tip 144 in the verticaldirection. Bottom edge 142 of each of first and second teeth 126 and 128includes first and second arcuate portions 146 and 148. First arcuateportion 146 extends from first side 132 to tip 144, and second arcuateportion 148 extends from tip 144 to second side 134 and has a radiussmaller than that of first arcuate portion 146 by 7-15%. In the mostpreferred form shown, the radius of first arcuate portion 146 is largerthan that of second arcuate portion 108 by about 9%. Thus, first tooth126 is planar and at a first acute angle B in a range of 55°-75°relative to base 122, and second tooth 128 is planar and at a secondacute angle C in a range of 55°-75° relative to base 122. In the mostpreferred form shown, each of first and second arcuate angles B and C isin the order of 66°. However, first and second acute angles B and C canbe different and different from each other.

Now that the basic construction of safety apparatus 10 of the preferredteachings of the present invention has been explained, the operation andsome of the advantages of safety apparatus 10 can be set forth andappreciated. In particular, for the sake of explanation, it will beassumed that slide 90 is in the upper position with engaging member 120above surface 102 (FIG. 1). If worker 100 falls from surface 102, forceresulting from falling of worker 100 is transmitted to slide 90 viaharness 80 and cable 62. Pulley 60 rotates about rotation axis 58. Slide90 is moved by cable 62 and slides from the upper position to the lowerposition (FIG. 8) along slide axis 92. First and second teeth 126 and128 of engaging member 120 on slide 90 dig into and, thus, grip surface102, preventing further falling of worker 100. Since engaging member 120directly digs into surface 102 along slide axis 92 at non-perpendicularangle A relative to surface 102, first and second teeth 126 and 128penetrate deeply into surface 102. Furthermore, since first and secondteeth 126 and 128 are at acute angles B and C relative to base 122,penetration of first and second teeth 126 and 128 into surface 102 isenhanced. Thus, engaging member 120 is securely held in place withoutunintentional removal, reliably arresting worker 100. Wedge-shapedbottom edges 142 with tips 144 also assist in gripping of surface 102 byfirst and second teeth 126 and 128, further enhancing the arrestingeffect of falling worker 100. It can be appreciated that attachmentmember 68 abuts with passage 86 to limit movement of slide 90 under biasof biasing member 110 during operation of safety apparatus 10 accordingto the preferred teachings of the present invention.

Now that the basic teachings of the present invention have beenexplained, many extensions and variations will be obvious to one havingordinary skill in the art. For example, slide 90 and/or engaging member20 can have different forms according to the teachings of the presentinvention. Specifically, engaging member 120 does not have to includebase 122, first and second teeth 126 and 128 can directly extend fromslide 90, slide 90 and/or engaging member 120 can have otherconstructions, or the like.

Although safety apparatus 10 in the preferred form shown includeslifting attachments 28 and is believed to produce synergistic results,lifting attachments 28 according to the teachings of the presentinvention can be utilized in other types of apparatus and equipment toavoid unintentional unhooking while being lifted to surface 102.Likewise, safety apparatus 10 according to the teachings of the presentinvention can include other types and forms of lifting attachments thanshown.

Thus since the invention disclosed herein may be embodied in otherspecific forms without departing from the spirit or generalcharacteristics thereof, some of which forms have been indicated, theembodiments described herein are to be considered in all respectsillustrative and not restrictive. The scope of the invention is to beindicated by the appended claims, rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are intended to be embraced therein.

1. A lifting attachment for a frame unit adapted to be lifted on asurface, with the lifting attachment comprising an attach elementcomprising, in combination: first and second sides spaced in a firstdirection; first and second edges each extending between the first andsecond sides, with the first and second edges spaced in a seconddirection perpendicular to the first direction; third and fourth edgeseach extending between the first and second sides and between the firstand second edges, with the third and fourth edges spaced in a thirddirection perpendicular to the first and second directions; a firstpassage extending between the first and second sides in the firstdirection and extending from the first edge towards but spaced from thesecond edge in the second direction, with the first passage spaced fromthe third and fourth edges in the third direction; and a second passageextending between the first and second sides in the first direction andextending from the first passage towards but spaced from the third edgein the second direction, with the second passage spaced from the first,second, and fourth edges.
 2. The lifting attachment as claimed in claim1, further comprising, in combination: an extension extending betweenthe first and second sides and extending from the first passage throughthe fourth edge in the third direction and extending from the first edgetowards but spaced from the second edge in the second direction, withthe second passage intermediate the extension and the second edge in thesecond direction.
 3. The lifting attachment as claimed in claim 2, withthe attachment element formed homogeneously from a same material andextending integrally between the first and second sides in the firstdirection, extending integrally between the first and second edges inthe second direction and extending integrally between the third edge andthe second passage in the third direction.